JP2742947B2 - Ultrasound blood flow imaging device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic blood flow imaging apparatus, and more particularly, to an ultrasonic blood flow imaging apparatus having a power masking function linked to a TGC (time gain control) function. Related to the device.

[Prior Art] FIG. 4 shows an example of a conventional ultrasonic blood flow imaging apparatus having a TGC function and a power masking function.

In the ultrasonic blood flow imaging apparatus 51, the probe 2
An ultrasonic echo signal is obtained by the electronic scanning unit 53, and the ultrasonic echo signal is amplified by the TGC amplifier 58 whose gain increases as the reception time is longer (the elapsed time after transmission is longer). (TGC Function) The ultrasonic echo signal output from the electronic scanning unit 53 is output to the B-mode processing unit 54 and to the phase detection unit 9 of the blood flow imaging processing unit.

The B-mode processing unit 54 obtains B-mode image data from the ultrasonic echo signal and outputs the data to the DSC 5.

The phase detector 9 detects the ultrasonic echo signal to obtain a blood flow Doppler signal, and converts the blood flow Doppler signal into a low-pass filter.
The signal is output to a CFM (color flow mapping) operation unit 13 via an A / D converter 11 and an MTI filter 12.

The CFM calculation unit 13 calculates the average velocity V, the variance σ, and the power P of the blood flow, and inputs them to the DSC 5.

The comparator 15 compares the power value P with a constant threshold value PTH output from the threshold value output unit 54.

The DSC 5 causes the color monitor 6 to perform a color flow display based on the average speed V and the like for pixels corresponding to the portion where PTH ≦ P. On the other hand, the pixels corresponding to the portions where P <PTH are not displayed in the color flow, but are displayed in the B mode (power masking function).

FIGS. 5 to 9 show the TG in the conventional device 51.
This explains the C function and the power masking function.

Since the ultrasonic echo signal is attenuated in accordance with the distance in the living body, even if the signal should have the same level, the level observed from the deeper part of the living body becomes lower. That is, the input signal levels of the TGC amplifier 58 are as shown at a, b, and c in FIG. Where a, b, c are relatively high, medium,
It is low. On the other hand, noise (random noise) is irrelevant to depth and becomes as shown in n in FIG.

The gain of the TGC amplifier 58 becomes larger as the reception time is later. This means that a signal from a deeper part of the living body is amplified with a larger gain, so that the relationship between the depth and the gain is as shown in FIG.

Therefore, the output signal level of the TGC amplifier 58 is
As shown in a, b, and c, the attenuation due to the depth is compensated, and the level is constant regardless of the depth. On the other hand, the level of the noise n is higher as it is deeper.

In order to prevent this noise n from being displayed on the color monitor 6, a threshold value PTH as shown in FIG.
Output.

As a result, as shown in FIG. 9, the noise n is masked, and the screen becomes easy to see.

[Problem to be Solved by the Invention] In the conventional device 51, the threshold value PTH is set to a level slightly higher than the maximum value of the level of the noise n (FIG. 8).

However, in this system, there is a problem that the signal c is uniformly masked in the shallow part of the living body even though it is larger than the noise n (FIG. 9).

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic blood flow imaging apparatus that prevents a signal from being masked uniformly as described above.

[Means for Solving the Problems] An ultrasonic imaging apparatus according to the present invention is a TGC that changes the amplification degree of an ultrasonic echo signal according to the reception time of the signal.
In an ultrasonic blood flow imaging apparatus having a power masking function in which a function and a power value are smaller than a threshold value and a color flow display is not performed, a threshold control means for changing a power masking threshold value in response to a gain change by a TGC function The configuration is characterized by the provision of.

[Operation] Due to the TGC function, the noise level changes in accordance with the change in gain due to the TGC function.

Therefore, if the threshold value is also changed in accordance with the change in the gain by the TGC function, it is possible to always use the threshold value as the threshold value of the noise level, thereby preventing the signal from being uniformly masked.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples shown in the drawings. It should be noted that the present invention is not limited by this.

FIG. 1 shows an ultrasonic blood flow imaging apparatus 1 according to one embodiment of the present invention.

The probe 2 and the electronic scanning unit 3 obtain an ultrasonic echo signal, and output the ultrasonic echo signal to the B-mode processing unit 4 and the TGC amplifier 8 of the blood flow imaging processing unit.

Further, the electronic scanning unit 3 outputs a trigger signal, which is a starting point of the reception time of the ultrasonic echo signal, to the control unit 7.

 The configuration and operation of the B-mode processing unit 4 are the same as those in the related art.

The control unit 7 outputs to the TGC amplifier 8 a control signal that increases the gain as the reception time of the ultrasonic echo signal is later. Further, a control signal for increasing the threshold value PTH by linking to the control signal is output to the threshold value output unit 14.

The TGC amplifier 8 amplifies the ultrasonic echo signal while increasing the gain.

Phase detector 9, low-pass filter 10, A / D converter 11, M
The configuration and operation of the TI filter 12 and the CFM calculation unit 13 are the same as those in the related art.

The threshold output unit 14 can be configured by interposing a variable gain amplifier such as a TGC amplifier 8 between the threshold output unit 54 and the comparator 15 in the conventional device 51 shown in FIG. The higher the signal reception time, the higher the threshold PTH is output.

Therefore, the threshold value PTH can be changed as shown in FIG. 2 for the signals a, b, c and the noise n shown in FIG.

The configuration and operation of the comparator 15 and the DSC 5 are the same as the conventional one, and the masking is performed by using the threshold value PTH linked to the TGC function.

As a result, as shown in FIG. 3, the signal c is not masked in the shallow part of the living body where the signal c is larger than the noise n, and appears in the color flow display. Moreover, the noise n is completely masked.

[Effects of the Invention] According to the ultrasonic blood flow imaging apparatus of the present invention, it is possible to mask the noise level from the shallow part to the deep part of the living body, and to prevent the signal from being excessively masked. Therefore, the blood flow detection ability can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ultrasonic imaging apparatus according to one embodiment of the present invention, FIG. 2 is a conceptual diagram showing a change in a threshold value PTH in the apparatus shown in FIG. 1, and FIG. FIG. 4 is a conceptual diagram showing the effect of masking, FIG. 4 is a block diagram of an example of a conventional ultrasonic blood flow imaging apparatus, and FIG.
The figure is a characteristic diagram of the depth of the observation point and the input signal level of the TGC amplifier. FIG. 6 is a correlation diagram of the depth and the gain of the TGC amplifier.
The figure is a characteristic diagram of the depth and the output signal level of the TGC amplifier.
The figure is a conceptual diagram of the threshold value PTH in the apparatus shown in FIG.
The figure is a conceptual diagram showing the effect of masking in the device shown in FIG. (Description of Signs) 1 ... Ultrasonic blood flow imaging apparatus 3 ... Electronic scanning unit 7 ... Control unit 8 ... TGC amplifier 14 ... Threshold output unit 15 ... Comparator PTH ... Threshold a, b, c ... Signal n ... Noise.

Claims (1)

(57) [Claims] An ultrasonic blood flow provided with a TGC function for changing the amplification degree of an ultrasonic echo signal in accordance with a reception time of the signal and a power masking function for not performing a color flow display on a portion where a power value is smaller than a threshold value. An ultrasonic blood flow imaging apparatus comprising: an imaging apparatus; and a threshold control means for changing a power masking threshold in response to a change in gain due to a TGC function.